To assess whether application of low frequency ultrasound extracts glucose across the human skin in vivo. To find out the minimum time required to extract sufficient amount of glucose across the skin by sonophoresis. To assess whether the amount of glucose extracted in this manner correlates with the blood glucose concentrations of patients. To assess whether a dynamic change in blood glucose level results in a detectable change in the amount of glucose extracted by sonophoresis and investigate the time lag between these two changes. To assess patient compliance related issues associated with using low-frequency sonophoresis for non-invasive blood-glucose measurements.